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/*
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 *
 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 *  * Neither the name of JSR-310 nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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package java.time.chrono;

import java.io.InvalidObjectException;

import static java.time.temporal.ChronoField.DAY_OF_MONTH;
import static java.time.temporal.ChronoField.ERA;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoField.PROLEPTIC_MONTH;
import static java.time.temporal.ChronoField.YEAR;
import static java.time.temporal.ChronoField.YEAR_OF_ERA;

import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.Clock;
import java.time.DateTimeException;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.Month;
import java.time.Period;
import java.time.Year;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.ResolverStyle;
import java.time.temporal.ChronoField;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalField;
import java.time.temporal.ValueRange;
import java.util.Arrays;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;

/**
 * The ISO calendar system. <p> This chronology defines the rules of the ISO calendar system. This
 * calendar system is based on the ISO-8601 standard, which is the <i>de facto</i> world calendar.
 * <p> The fields are defined as follows: <ul> <li>era - There are two eras, 'Current Era' (CE) and
 * 'Before Current Era' (BCE). <li>year-of-era - The year-of-era is the same as the proleptic-year
 * for the current CE era. For the BCE era before the ISO epoch the year increases from 1 upwards as
 * time goes backwards. <li>proleptic-year - The proleptic year is the same as the year-of-era for
 * the current era. For the previous era, years have zero, then negative values. <li>month-of-year -
 * There are 12 months in an ISO year, numbered from 1 to 12. <li>day-of-month - There are between
 * 28 and 31 days in each of the ISO month, numbered from 1 to 31. Months 4, 6, 9 and 11 have 30
 * days, Months 1, 3, 5, 7, 8, 10 and 12 have 31 days. Month 2 has 28 days, or 29 in a leap year.
 * <li>day-of-year - There are 365 days in a standard ISO year and 366 in a leap year. The days are
 * numbered from 1 to 365 or 1 to 366. <li>leap-year - Leap years occur every 4 years, except where
 * the year is divisble by 100 and not divisble by 400. </ul>
 *
 * @implSpec This class is immutable and thread-safe.
 * @since 1.8
 */
public final class IsoChronology extends AbstractChronology implements Serializable {

  /**
   * Singleton instance of the ISO chronology.
   */
  public static final IsoChronology INSTANCE = new IsoChronology();

  /**
   * Serialization version.
   */
  private static final long serialVersionUID = -1440403870442975015L;

  /**
   * Restricted constructor.
   */
  private IsoChronology() {
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the ID of the chronology - 'ISO'.
   * <p>
   * The ID uniquely identifies the {@code Chronology}.
   * It can be used to lookup the {@code Chronology} using {@link Chronology#of(String)}.
   *
   * @return the chronology ID - 'ISO'
   * @see #getCalendarType()
   */
  @Override
  public String getId() {
    return "ISO";
  }

  /**
   * Gets the calendar type of the underlying calendar system - 'iso8601'.
   * <p>
   * The calendar type is an identifier defined by the
   * <em>Unicode Locale Data Markup Language (LDML)</em> specification.
   * It can be used to lookup the {@code Chronology} using {@link Chronology#of(String)}.
   * It can also be used as part of a locale, accessible via
   * {@link Locale#getUnicodeLocaleType(String)} with the key 'ca'.
   *
   * @return the calendar system type - 'iso8601'
   * @see #getId()
   */
  @Override
  public String getCalendarType() {
    return "iso8601";
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains an ISO local date from the era, year-of-era, month-of-year
   * and day-of-month fields.
   *
   * @param era the ISO era, not null
   * @param yearOfEra the ISO year-of-era
   * @param month the ISO month-of-year
   * @param dayOfMonth the ISO day-of-month
   * @return the ISO local date, not null
   * @throws DateTimeException if unable to create the date
   * @throws ClassCastException if the type of {@code era} is not {@code IsoEra}
   */
  @Override  // override with covariant return type
  public LocalDate date(Era era, int yearOfEra, int month, int dayOfMonth) {
    return date(prolepticYear(era, yearOfEra), month, dayOfMonth);
  }

  /**
   * Obtains an ISO local date from the proleptic-year, month-of-year
   * and day-of-month fields.
   * <p>
   * This is equivalent to {@link LocalDate#of(int, int, int)}.
   *
   * @param prolepticYear the ISO proleptic-year
   * @param month the ISO month-of-year
   * @param dayOfMonth the ISO day-of-month
   * @return the ISO local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate date(int prolepticYear, int month, int dayOfMonth) {
    return LocalDate.of(prolepticYear, month, dayOfMonth);
  }

  /**
   * Obtains an ISO local date from the era, year-of-era and day-of-year fields.
   *
   * @param era the ISO era, not null
   * @param yearOfEra the ISO year-of-era
   * @param dayOfYear the ISO day-of-year
   * @return the ISO local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate dateYearDay(Era era, int yearOfEra, int dayOfYear) {
    return dateYearDay(prolepticYear(era, yearOfEra), dayOfYear);
  }

  /**
   * Obtains an ISO local date from the proleptic-year and day-of-year fields.
   * <p>
   * This is equivalent to {@link LocalDate#ofYearDay(int, int)}.
   *
   * @param prolepticYear the ISO proleptic-year
   * @param dayOfYear the ISO day-of-year
   * @return the ISO local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate dateYearDay(int prolepticYear, int dayOfYear) {
    return LocalDate.ofYearDay(prolepticYear, dayOfYear);
  }

  /**
   * Obtains an ISO local date from the epoch-day.
   * <p>
   * This is equivalent to {@link LocalDate#ofEpochDay(long)}.
   *
   * @param epochDay the epoch day
   * @return the ISO local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate dateEpochDay(long epochDay) {
    return LocalDate.ofEpochDay(epochDay);
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains an ISO local date from another date-time object.
   * <p>
   * This is equivalent to {@link LocalDate#from(TemporalAccessor)}.
   *
   * @param temporal the date-time object to convert, not null
   * @return the ISO local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate date(TemporalAccessor temporal) {
    return LocalDate.from(temporal);
  }

  /**
   * Obtains an ISO local date-time from another date-time object.
   * <p>
   * This is equivalent to {@link LocalDateTime#from(TemporalAccessor)}.
   *
   * @param temporal the date-time object to convert, not null
   * @return the ISO local date-time, not null
   * @throws DateTimeException if unable to create the date-time
   */
  @Override  // override with covariant return type
  public LocalDateTime localDateTime(TemporalAccessor temporal) {
    return LocalDateTime.from(temporal);
  }

  /**
   * Obtains an ISO zoned date-time from another date-time object.
   * <p>
   * This is equivalent to {@link ZonedDateTime#from(TemporalAccessor)}.
   *
   * @param temporal the date-time object to convert, not null
   * @return the ISO zoned date-time, not null
   * @throws DateTimeException if unable to create the date-time
   */
  @Override  // override with covariant return type
  public ZonedDateTime zonedDateTime(TemporalAccessor temporal) {
    return ZonedDateTime.from(temporal);
  }

  /**
   * Obtains an ISO zoned date-time in this chronology from an {@code Instant}.
   * <p>
   * This is equivalent to {@link ZonedDateTime#ofInstant(Instant, ZoneId)}.
   *
   * @param instant the instant to create the date-time from, not null
   * @param zone the time-zone, not null
   * @return the zoned date-time, not null
   * @throws DateTimeException if the result exceeds the supported range
   */
  @Override
  public ZonedDateTime zonedDateTime(Instant instant, ZoneId zone) {
    return ZonedDateTime.ofInstant(instant, zone);
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains the current ISO local date from the system clock in the default time-zone.
   * <p>
   * This will query the {@link Clock#systemDefaultZone() system clock} in the default
   * time-zone to obtain the current date.
   * <p>
   * Using this method will prevent the ability to use an alternate clock for testing
   * because the clock is hard-coded.
   *
   * @return the current ISO local date using the system clock and default time-zone, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate dateNow() {
    return dateNow(Clock.systemDefaultZone());
  }

  /**
   * Obtains the current ISO local date from the system clock in the specified time-zone.
   * <p>
   * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date.
   * Specifying the time-zone avoids dependence on the default time-zone.
   * <p>
   * Using this method will prevent the ability to use an alternate clock for testing
   * because the clock is hard-coded.
   *
   * @return the current ISO local date using the system clock, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate dateNow(ZoneId zone) {
    return dateNow(Clock.system(zone));
  }

  /**
   * Obtains the current ISO local date from the specified clock.
   * <p>
   * This will query the specified clock to obtain the current date - today.
   * Using this method allows the use of an alternate clock for testing.
   * The alternate clock may be introduced using {@link Clock dependency injection}.
   *
   * @param clock the clock to use, not null
   * @return the current ISO local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public LocalDate dateNow(Clock clock) {
    Objects.requireNonNull(clock, "clock");
    return date(LocalDate.now(clock));
  }

  //-----------------------------------------------------------------------

  /**
   * Checks if the year is a leap year, according to the ISO proleptic
   * calendar system rules.
   * <p>
   * This method applies the current rules for leap years across the whole time-line.
   * In general, a year is a leap year if it is divisible by four without
   * remainder. However, years divisible by 100, are not leap years, with
   * the exception of years divisible by 400 which are.
   * <p>
   * For example, 1904 is a leap year it is divisible by 4.
   * 1900 was not a leap year as it is divisible by 100, however 2000 was a
   * leap year as it is divisible by 400.
   * <p>
   * The calculation is proleptic - applying the same rules into the far future and far past.
   * This is historically inaccurate, but is correct for the ISO-8601 standard.
   *
   * @param prolepticYear the ISO proleptic year to check
   * @return true if the year is leap, false otherwise
   */
  @Override
  public boolean isLeapYear(long prolepticYear) {
    return ((prolepticYear & 3) == 0) && ((prolepticYear % 100) != 0 || (prolepticYear % 400) == 0);
  }

  @Override
  public int prolepticYear(Era era, int yearOfEra) {
    if (era instanceof IsoEra == false) {
      throw new ClassCastException("Era must be IsoEra");
    }
    return (era == IsoEra.CE ? yearOfEra : 1 - yearOfEra);
  }

  @Override
  public IsoEra eraOf(int eraValue) {
    return IsoEra.of(eraValue);
  }

  @Override
  public List<Era> eras() {
    return Arrays.<Era>asList(IsoEra.values());
  }

  //-----------------------------------------------------------------------

  /**
   * Resolves parsed {@code ChronoField} values into a date during parsing.
   * <p>
   * Most {@code TemporalField} implementations are resolved using the
   * resolve method on the field. By contrast, the {@code ChronoField} class
   * defines fields that only have meaning relative to the chronology.
   * As such, {@code ChronoField} date fields are resolved here in the
   * context of a specific chronology.
   * <p>
   * {@code ChronoField} instances on the ISO calendar system are resolved
   * as follows.
   * <ul>
   * <li>{@code EPOCH_DAY} - If present, this is converted to a {@code LocalDate}
   * and all other date fields are then cross-checked against the date.
   * <li>{@code PROLEPTIC_MONTH} - If present, then it is split into the
   * {@code YEAR} and {@code MONTH_OF_YEAR}. If the mode is strict or smart
   * then the field is validated.
   * <li>{@code YEAR_OF_ERA} and {@code ERA} - If both are present, then they
   * are combined to form a {@code YEAR}. In lenient mode, the {@code YEAR_OF_ERA}
   * range is not validated, in smart and strict mode it is. The {@code ERA} is
   * validated for range in all three modes. If only the {@code YEAR_OF_ERA} is
   * present, and the mode is smart or lenient, then the current era (CE/AD)
   * is assumed. In strict mode, no era is assumed and the {@code YEAR_OF_ERA} is
   * left untouched. If only the {@code ERA} is present, then it is left untouched.
   * <li>{@code YEAR}, {@code MONTH_OF_YEAR} and {@code DAY_OF_MONTH} -
   * If all three are present, then they are combined to form a {@code LocalDate}.
   * In all three modes, the {@code YEAR} is validated. If the mode is smart or strict,
   * then the month and day are validated, with the day validated from 1 to 31.
   * If the mode is lenient, then the date is combined in a manner equivalent to
   * creating a date on the first of January in the requested year, then adding
   * the difference in months, then the difference in days.
   * If the mode is smart, and the day-of-month is greater than the maximum for
   * the year-month, then the day-of-month is adjusted to the last day-of-month.
   * If the mode is strict, then the three fields must form a valid date.
   * <li>{@code YEAR} and {@code DAY_OF_YEAR} -
   * If both are present, then they are combined to form a {@code LocalDate}.
   * In all three modes, the {@code YEAR} is validated.
   * If the mode is lenient, then the date is combined in a manner equivalent to
   * creating a date on the first of January in the requested year, then adding
   * the difference in days.
   * If the mode is smart or strict, then the two fields must form a valid date.
   * <li>{@code YEAR}, {@code MONTH_OF_YEAR}, {@code ALIGNED_WEEK_OF_MONTH} and
   * {@code ALIGNED_DAY_OF_WEEK_IN_MONTH} -
   * If all four are present, then they are combined to form a {@code LocalDate}.
   * In all three modes, the {@code YEAR} is validated.
   * If the mode is lenient, then the date is combined in a manner equivalent to
   * creating a date on the first of January in the requested year, then adding
   * the difference in months, then the difference in weeks, then in days.
   * If the mode is smart or strict, then the all four fields are validated to
   * their outer ranges. The date is then combined in a manner equivalent to
   * creating a date on the first day of the requested year and month, then adding
   * the amount in weeks and days to reach their values. If the mode is strict,
   * the date is additionally validated to check that the day and week adjustment
   * did not change the month.
   * <li>{@code YEAR}, {@code MONTH_OF_YEAR}, {@code ALIGNED_WEEK_OF_MONTH} and
   * {@code DAY_OF_WEEK} - If all four are present, then they are combined to
   * form a {@code LocalDate}. The approach is the same as described above for
   * years, months and weeks in {@code ALIGNED_DAY_OF_WEEK_IN_MONTH}.
   * The day-of-week is adjusted as the next or same matching day-of-week once
   * the years, months and weeks have been handled.
   * <li>{@code YEAR}, {@code ALIGNED_WEEK_OF_YEAR} and {@code ALIGNED_DAY_OF_WEEK_IN_YEAR} -
   * If all three are present, then they are combined to form a {@code LocalDate}.
   * In all three modes, the {@code YEAR} is validated.
   * If the mode is lenient, then the date is combined in a manner equivalent to
   * creating a date on the first of January in the requested year, then adding
   * the difference in weeks, then in days.
   * If the mode is smart or strict, then the all three fields are validated to
   * their outer ranges. The date is then combined in a manner equivalent to
   * creating a date on the first day of the requested year, then adding
   * the amount in weeks and days to reach their values. If the mode is strict,
   * the date is additionally validated to check that the day and week adjustment
   * did not change the year.
   * <li>{@code YEAR}, {@code ALIGNED_WEEK_OF_YEAR} and {@code DAY_OF_WEEK} -
   * If all three are present, then they are combined to form a {@code LocalDate}.
   * The approach is the same as described above for years and weeks in
   * {@code ALIGNED_DAY_OF_WEEK_IN_YEAR}. The day-of-week is adjusted as the
   * next or same matching day-of-week once the years and weeks have been handled.
   * </ul>
   *
   * @param fieldValues the map of fields to values, which can be updated, not null
   * @param resolverStyle the requested type of resolve, not null
   * @return the resolved date, null if insufficient information to create a date
   * @throws DateTimeException if the date cannot be resolved, typically because of a conflict in
   * the input data
   */
  @Override  // override for performance
  public LocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
    return (LocalDate) super.resolveDate(fieldValues, resolverStyle);
  }

  @Override
    // override for better proleptic algorithm
  void resolveProlepticMonth(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
    Long pMonth = fieldValues.remove(PROLEPTIC_MONTH);
    if (pMonth != null) {
      if (resolverStyle != ResolverStyle.LENIENT) {
        PROLEPTIC_MONTH.checkValidValue(pMonth);
      }
      addFieldValue(fieldValues, MONTH_OF_YEAR, Math.floorMod(pMonth, 12) + 1);
      addFieldValue(fieldValues, YEAR, Math.floorDiv(pMonth, 12));
    }
  }

  @Override
    // override for enhanced behaviour
  LocalDate resolveYearOfEra(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
    Long yoeLong = fieldValues.remove(YEAR_OF_ERA);
    if (yoeLong != null) {
      if (resolverStyle != ResolverStyle.LENIENT) {
        YEAR_OF_ERA.checkValidValue(yoeLong);
      }
      Long era = fieldValues.remove(ERA);
      if (era == null) {
        Long year = fieldValues.get(YEAR);
        if (resolverStyle == ResolverStyle.STRICT) {
          // do not invent era if strict, but do cross-check with year
          if (year != null) {
            addFieldValue(fieldValues, YEAR, (year > 0 ? yoeLong : Math.subtractExact(1, yoeLong)));
          } else {
            // reinstate the field removed earlier, no cross-check issues
            fieldValues.put(YEAR_OF_ERA, yoeLong);
          }
        } else {
          // invent era
          addFieldValue(fieldValues, YEAR,
              (year == null || year > 0 ? yoeLong : Math.subtractExact(1, yoeLong)));
        }
      } else if (era.longValue() == 1L) {
        addFieldValue(fieldValues, YEAR, yoeLong);
      } else if (era.longValue() == 0L) {
        addFieldValue(fieldValues, YEAR, Math.subtractExact(1, yoeLong));
      } else {
        throw new DateTimeException("Invalid value for era: " + era);
      }
    } else if (fieldValues.containsKey(ERA)) {
      ERA.checkValidValue(fieldValues.get(ERA));  // always validated
    }
    return null;
  }

  @Override
    // override for performance
  LocalDate resolveYMD(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
    int y = YEAR.checkValidIntValue(fieldValues.remove(YEAR));
    if (resolverStyle == ResolverStyle.LENIENT) {
      long months = Math.subtractExact(fieldValues.remove(MONTH_OF_YEAR), 1);
      long days = Math.subtractExact(fieldValues.remove(DAY_OF_MONTH), 1);
      return LocalDate.of(y, 1, 1).plusMonths(months).plusDays(days);
    }
    int moy = MONTH_OF_YEAR.checkValidIntValue(fieldValues.remove(MONTH_OF_YEAR));
    int dom = DAY_OF_MONTH.checkValidIntValue(fieldValues.remove(DAY_OF_MONTH));
    if (resolverStyle == ResolverStyle.SMART) {  // previous valid
      if (moy == 4 || moy == 6 || moy == 9 || moy == 11) {
        dom = Math.min(dom, 30);
      } else if (moy == 2) {
        dom = Math.min(dom, Month.FEBRUARY.length(Year.isLeap(y)));

      }
    }
    return LocalDate.of(y, moy, dom);
  }

  //-----------------------------------------------------------------------
  @Override
  public ValueRange range(ChronoField field) {
    return field.range();
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains a period for this chronology based on years, months and days.
   * <p>
   * This returns a period tied to the ISO chronology using the specified
   * years, months and days. See {@link Period} for further details.
   *
   * @param years the number of years, may be negative
   * @param months the number of years, may be negative
   * @param days the number of years, may be negative
   * @return the ISO period, not null
   */
  @Override  // override with covariant return type
  public Period period(int years, int months, int days) {
    return Period.of(years, months, days);
  }

  //-----------------------------------------------------------------------

  /**
   * Writes the Chronology using a
   * <a href="../../../serialized-form.html#java.time.chrono.Ser">dedicated serialized form</a>.
   *
   * @return the instance of {@code Ser}, not null
   * @serialData <pre>
   *  out.writeByte(1);     // identifies a Chronology
   *  out.writeUTF(getId());
   * </pre>
   */
  @Override
  Object writeReplace() {
    return super.writeReplace();
  }

  /**
   * Defend against malicious streams.
   *
   * @param s the stream to read
   * @throws InvalidObjectException always
   */
  private void readObject(ObjectInputStream s) throws InvalidObjectException {
    throw new InvalidObjectException("Deserialization via serialization delegate");
  }
}
